Such exhaust flap devices are used, for example, as exhaust retention flaps, as exhaust recirculation valves in low pressure or high pressure exhaust circuits, or as throttle valves in the intake system of internal combustion engines. They serve to control a quantity of exhaust gas to be recirculated to the cylinders, to control the pressure in the exhaust recirculation duct for a reduction of the pollutant emissions of the engine, or to control the quantity of air taken in.
Depending on the installation position, these valves are subjected to different loads both with respect to the incidental quantity of pollutants and the temperatures prevailing. High thermal loads may cause thermal expansions that may lead to a jamming of the shaft in particular in the case of valves arranged in the exhaust gas region. It is further necessary for valves that are not thermally loaded and are supported only at one side to provide a simple rotatability by providing a reliable bearing which avoids misalignment.
DE 10 2007 000 221 A1 describes a flap device which has two bearings arranged at one side of the flap body. The two bearings are arranged in a housing which simultaneously forms the flow housing and the actuator housing. An active cooling by cooling water must correspondingly be provided for such a valve if it is to be used in a thermally loaded region.
DE 10 2009 011 951 A1 therefore describes an exhaust flap device in which the actuator housing is formed separately from the flow housing. Using a mounting frame welded to the flow housing, the two housings are fastened to each other by two radially extending screws, and the flap shaft is connected with the shaft of the actuator by a coupling. The shaft is completely supported in the flow housing at the two axial ends of the shaft. Such a design does not provide that the flow housing is correctly aligned with the actuator housing in order to obtain a correct connection of the drive.
Known designs are therefore disadvantageous in that either a thermal overload must be expected if no active cooling is used, or that it is not possible to provide a correctly aligned connection of the actuator housing with the flow housing or of the existing shafts and to thereby provide the free movement of the actuator and the flap over a long service life. In particular with flaps mounted at two sides, problems may also arise during assembly or by thermal expansions occurring in operation. It is necessary with coupled shafts that both shafts are fully mounted separate from each other when gearings are used.